Protocol Number: 07-N-0063

Title:

Detecting a Reward Signal in the Motor Cortex

Number:

07-N-0063

Summary:

This study will use transcranial magnetic stimulation (TMS) to determine whether the activity in the brain when someone wins something affects the part of the brain that controls movement. Studies have shown that the brain releases signals to mark rewards for certain behavior, like the activity the brain generates when an animal receives food or drink after performing a certain action. This study will look for a way to detect this kind of signal in humans.

Healthy volunteers between 18 and 60 years of age are eligible for this study. Participants undergo TMS during two experiments - slot machine stimulation and key sequence (see below). For TMS, a wire coil is held on the subject's scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. The stimulation may cause twitching in muscles of the face, arm or leg, and there may be a pulling sensation on the skin under the coil. The effect of TMS on the muscles is detected with small metal disk electrodes taped onto the skin of the arms or legs.

The stimulation strength needed to activate the hand muscles is determined at the beginning of each experiment. To do this, the subject sits with his or her arms and hand relaxed. Magnetic pulses of varying strengths are applied in order to find the right strength. Also, a series of 45 pairs of magnetic pulses is administered so close to each other that they produce only one movement. Measurements of the movements generated serve as a baseline for comparison with movements generated during the experiments.

Slot Machine Simulation

Subjects play a computer game similar to a slot machine. They press a button to start the game and watch as three barrels of the machine spin into place. Subjects can win $0.25, $1or $5 if all three barrels match when they stop spinning. If all three barrels do not match, subjects do not win any money, except in rare instances, when they are awarded money even when all three barrels do not match. In one trial in this experiment, subjects receive transcranial magnetic stimulation after they see the second barrel stop spinning. In another trial, they receive the stimulation after the third barrel stops spinning.

Key Sequence

Subjects see a letter on a computer screen and press a combination of the three keyboard keys G, H, and J. If they press the keys in the right order and under the time limit, they win $1. At some point, the letter displayed changes, and the subjects must guess a new combination to earn money. Each of the letters corresponds to its own combination of key presses. A few moments after the subjects see whether they pressed the keys in the right order, they receive TMS.

Sponsoring Institute:

National Institute of Neurological Disorders and Stroke (NINDS)

Recruitment Detail

Type: Participants currently recruited/enrolled

Gender: Male

Referral Letter Required: No

Population Exclusion(s): Children

Female

Eligibility Criteria:

INCLUSION CRITERIA:

Men, age 18-60.

EXCLUSION CRITERIA:

Significant neurological or psychiatric history.

History of habitual gambling, defined as either visiting casinos more than once per month or playing cards for money more than once per week or gambling over the internet more than once per month.

Habitual consumption of more than two drinks a day, marijuana more than once a week or any other illicit drug use within the last three months.

Use of medication affecting the DA system, such as phenothiazine antihistamines (promethazine), antiemetics or decongestants within the last month.

Seizure History.

Significant abnormality on neurological examination.

Metal in the cranial cavity or eye, pacemaker, implanted pumps or stimulators.

Subjects who have participated in any other experiments in this protocol may not participate in experiment 4.

Special Instructions:

Currently Not Provided

Keywords:

Transcranial Magnetic Stimulation (TMS)

Dopamine

Gambling

Recruitment Keyword(s):

Healthy Volunteer

HV

Condition(s):

Healthy

Investigational Drug(s):

None

Investigational Device(s):

None

Intervention(s):

None

Supporting Site:

National Institute of Neurological Disorders and Stroke

Contact(s):

Patient Recruitment and Public Liaison Office
Building 61
10 Cloister Court
Bethesda, Maryland 20892-4754
Toll Free: 1-800-411-1222
TTY: 301-594-9774 (local),1-866-411-1010 (toll free)
Fax: 301-480-9793

Electronic Mail:prpl@mail.cc.nih.gov

Citation(s):

Avanzi M, Uber E, Bonfa F. Pathological gambling in two patients on dopamine replacement therapy for Parkinson's disease. Neurol Sci. 2004 Jun;25(2):98-101.

Cohen MX, Young J, Baek JM, Kessler C, Ranganath C. Individual differences in extraversion and dopamine genetics predict neural reward responses. Brain Res Cogn Brain Res. 2005 Dec;25(3):851-61. Epub 2005 Nov 11.

Strobel A, Spinath FM, Angleitner A, Riemann R, Lesch KP. Lack of association between polymorphisms of the dopamine D4 receptor gene and personality. Neuropsychobiology. 2003;47(1):52-6.

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